1. CPT EIT LWI

2. |2> |1> |3>

3. CPT Suppose then solving Schrodinger Equation What if we’re sneaky and choose Such that c 1 (t)=0. Then we are trapped in the two lower states. Population Trapping

4. CPT In fact So Is an eigenstate of the interaction Hamiltonian Dark States

5. CPT Coherent Population Dark State density matrix at t=0 Incoherent mixture density matrix at t=0 Rabi OscillationsTrapped in dark state

6. EIT |2> |1> |3> weak strong

7. EIT Re[n]-1 Im[n]

8. EIT quant-ph/0204173

9. LWI We can completely eliminate absorption, can we do better? |2> |1> |3> The idea: Pump atoms into dark state, then emission from |1> can exceed absorption from ground states.

10. BIB Quantum Optics, Scully and Zubairy,Cambridge University press 1997 Resolving conundrums in lasing without inversion via exact solutions to simple models, Scully, Quantum Opt. 6 p 203, 1994 Slow, Ultraslow, stored, and Frozen Light, Matsko,et. al., Adv.Atm.Mol.Opt.Phys. 47, p191 2001 Electromagnetically Induced Transparency, Harris, Physics Today, July 1997, p36